Centered in the city of Stormreach, DDO is set on the fictional continent of Xen'drik, in the world of Eberron, a setting from the Dungeons & Dragons tabletop role-playing game. Xen'drik is a vastly unexplored locale, once the center of the Advanced GiantCivilization, destroyed thousands of years before. Stormreach is a giant-scaled city, recently settled by humans. Areas in Stormreach are the Harbor, the Marketplace, and five Dragonmarked Houses: Cannith, Deneith, Jorasco, Kundarak and Phiarlan. Adventures and quests are available beyond the city walls, across the continent.

Players create their characters following the revised edition of D&D 3.5 rule-set fashion, for play in both indoor and outdoorenvironments. The game has some differences from the D&D 3.5 rule set, some of which are due to differences in the dynamics of video game combat versus tabletop gaming. For example, Turbine wanted DDO to use a real-time combat engine, whereas tabletop D&D uses a turn-based system. This meant considerable changes in the handling of combat and character skills; differences include increased hit possibilities in a round, increased spell casting resources over rest periods, and the use of a spell point system instead of spell slots. Other differences, not mandated by the differences by real-time versus turn-based systems include: magical items are at a lower cost (averaging 1/8 of the tabletop D&D prices), characters have higher stats, and offensive effects created by characters do not harm their allies.

After creating a player character (PC), a player begins shipwrecked on the shores of Korthos Island. The character is helped by a band of citizens (Jeets, Cellimas, and Talbron) who want to end the rule of the Sahuagin on Korthos Island. The White dragon Aussircaex is being controlled by a Mindflayer Creature through the use of a Mindsunder Artifact, and is plaguing the island. Once the PC destroys the Mindsunder Artifact, Aussircaex destroys the Mindflayer and frees Korthos Island, ending Sahuagin rule. After achieving success in Korthos Island, the player is sent to Stormreach.

From that point on, events in the game revolve around Stormreach. The player has to save the city from many threats, including:

Giants attempt to regain mastery over the city of Stormreach and the continent of Xen'drik.

DDO is an Action role-playing game with real-time combat. The camera follows behind the player and can be adjusted to view surroundings, or can be changed to a first-person perspective. The game can be controlled either by keyboard or gamepad, with the ability to remap actions to suit the player. Items and action abilities may be placed and activated within a toolbar on screen. Characters move in 3D via directional keys and may dodge long range attacks. A party system emphasizes multiple players forming groups, by accessing by the grouping panel. Players interact via screen chat windows, or by voice chat among party members.

Progress is defined by completing quests and leveling up. After creating a character, players are required to go through a tutorial, and then receive quests from non-player characters. After accumulating enough experience points through quests, the character gains a level, which grants access to feats, spells, and skills. The game initially limited characters to a maximum level of 10, but has since increased the limit to 28.[1] Each module has added quests and areas. Unlike most other RPGs, experience points are not gained by killing monsters, but rather by completing quests.[1][2] Another difference is that characters do not automatically heal from damage, but instead must visit special locations to do so.[3]

Quests in DDO are organized by character level, difficulty, length, and patron. Each quest has a base level, with the XP reward lessened if any of the party members are above that level. Characters more than two levels below the "base level" are not allowed to initiate a quest, but they are able to join a quest started by another party member. Characters more than three levels below the highest level character are penalized for being "powerleveled", and get significantly less XP.[citation needed]

Most quests have an item or monetary reward when completed, and the character must talk to the quest giver to receive the reward. Some dungeons require several visits to the quest giver to complete the entire quest chain. Speaking to the quest giver allows players to repeat the quest, although each time through reduces the amount of XP and loot awarded. Once enough quests are completed, the character will attract the attention of patrons, who give special rewards, such as long-lasting spells or exclusive items, and in some cases, unlocking special races or classes (which can also be purchased through the DDO Store).[citation needed]

The six difficulty levels for quests are: solo, casual, normal, hard, elite, and epic. Epic quests are further divided into epic normal, epic hard and Epic Elite. Solo and epic are only available on a small number of quests; solo quests must be completed alone, and are rare outside tutorials, while epic quests are offered once level 20 is reached. All difficulty levels give an XP bonus the first time the quest is run at the given level, but elite gives a much higher bonus. Higher difficulty levels provide a much more challenging experience to the players, with monsters making use of more powerful spells and traps. The quality of the loot (items, equipment, etc.) increases depending on difficulty level.[citation needed]

Casual level offers decreased XP and loot, with some powerful items not appearing in casual at all. Casual is frequently used by newer players to learn the game, or by higher-level characters to quickly achieve prerequisites for raids or to farm materials used in crafting.[citation needed]

Added with Update 19, sagas provide extra experience or item bonuses just for completing the required quests. There are 6 sagas,[6] with different bonuses depending on what difficulty setting they are attempted on. Sagas provide an incentive for completing entire questlines.[7]

Added with Update 15, the Monster Manual provides bonuses for killing a certain number of monsters as well as new types of monsters. Character deeds give bonuses of experience depending on the number of monsters killed of a certain type, while account deeds provide bonuses of Astral Shards for use in the Shard Exchange, or Jewels of Fortune which increase the level of loot you get from quest chests. Once all account deeds have been accomplished for a certain type of creature, players are allowed to see the total amount of Hit Points that type of creature has. The Monster Manual is exclusive to VIP members, or can be bought from the DDO store.[8]

DDO is an instanced game, where each party receives a private "copy" of a dungeon for their own use. Marketing, socializing, and quest selection are done in community areas.

The game is available in English. The French and German localized versions have been discontinued.[9]

As of September 9, 2009, DDO is free to play, with a micro-transaction store; players can gain VIP status by paying a subscription fee, which garners them additional rewards every month. A free-player's first micro-transaction converts them to a "Premium player" with additional perks (though less than those of a "VIP"). [10]

There are eight DDOgame servers, named after geographic aspects or organizations of Eberron. Turbine deploys the game and maintains daily operations of all servers.

The servers used to be geographically distributed, with 14 in North America, 5 in Europe, with others in China and Japan. There were no servers for the Southern Hemisphere market. The game distributed in Australia by Atari was the US version. The servers in North America, were operated by Turbine, while those in Europe were maintained by Codemasters and Alchemic Dream. In China, the game was operated by Shanda, and in Japan by Sakura Internet. When the European servers went offline in 2010, players were able to transfer their characters to the American servers.

The Shadowfell Conspiracy expansion introduced 4 variant races called Iconic Heroes: Bladeforged, Purple Dragon Knight, Shadar-kai, and Sun Elf.[12] These races must be purchased. They require the player to start their first level as a certain class. If the PC decides to follow the path the Iconic Hero is designed for, all 15 levels will be taken in this class. After level 1, however, players are free to take any class they wish.

There are 14 playable classes open to all races.[13] Players choose an initial class, but do not have to remain in that class. The Favored Souls and Artificers classes must either be unlocked or purchased, while Monks and Druids are premium classes requiring either an active subscription or purchase in the online store.

Multiclassing: A character can take levels in up to 3 different classes. There are no experience penalties for multiclass characters. Apart from alignment, there are no restrictions on multi-class combinations.

At the character creation screen, the player is allowed to choose a path or to customize their stats. Choosing a path automatically gives the character feats when they gain a level. "Veteran Status" (purchased or unlocked via gameplay) allows a player to start a character at level 4 or level 7 instead of level 1.[14] Iconic Heroes can start at level 15.

Progressive systems are in place in DDO providing additional variety between characters. Feats are special abilities that grant a character additional actions or abilities. Skills can be increased to give higher bonuses or satisfy prerequisites. Enhancements can be chosen to augment feats and class-based abilities.

Feats are divided into regular and class feats. Regular feats are available to any class, but class feats can only be chosen by specific classes. Every class is granted at least one feat during character creation, as well as one every third level.

Skills, such as one's ability to jump or find secret doors, are increased whenever a new level is gained. Each skill has a governing attribute, which may apply a bonus or penalty. Some skills are limited to success or failure, while others give incremental bonuses with each skill point. A character's skills are based on class, with cross-class skills costing twice as much to increase. The number of skill points one can distribute is limited by class and the Intelligence attribute.

Enhancements, a mechanic which does not exist in the tabletop version, further customize characters. Levels have five tiers, and each tier reached grants one "action point", for a total of four points per level. These can be used in enhancement trees to provide bonuses to skills or special abilities. Each class has a certain number of enhancement trees to further enhance the PC, and every PC gets one race tree providing racial bonuses. A player is given a total of 80 enhancement points through level 20.[15]

Epic levels and Destinies were added with Update 14. They allow a player to further specialize their character after level 20.

Epic destinies earn equivalent but separate XP from Epic Levels. Upon completing a tier in a particular destiny, an action point is given that can only be spent in that epic destiny. A player can earn a total of 24 action points in a tree, with only one destiny active at one time. A player may choose to switch to an adjacent destiny on the epic destiny map once a certain number of levels have been achieved, or by purchasing a special item from the DDO. A player is given 3 total Twists of Fate that let the player choose 3 skills from the first 3 tiers of Epic Destiny trees to use even if that Epic Destiny is no longer active, providing bonuses from other trees that players would otherwise no longer get.[16]

Reincarnation is a game mechanic allowing PCs to either respec their existing character (select different feats or skills) or to sacrifice experience and start the character anew on a lower level (new life), in return for an extra ability (a bonus past-life feat). Players have access to several types of reincarnation: lesser, true (heroic or iconic), and epic.[17]

Lesser reincarnation allows players to change the appearance of their character, re-spend their ability points, change their feats, reallocate skill points, redo their spell selection, or select a new path. They do not lose any experience or levels through lesser reincarnation. After re-leveling, the player can re-allocate earned enhancement points. Lesser Reincarnation also increases the starting build points from 28 to 32 for non-Drow characters.[citation needed]

True reincarnation is only available to level 20 characters for standard races or level 28 for iconic races. It completely erases the character as it was. A special reincarnation bank cache is created to hold anything from the PC's backpack or equipment, to be retrieved whenever the player wishes. This reincarnation upgrades the character's build from the previous build point (e.g. from 28 or 32 to 34, and 34 to 36), allowing higher starting ability points. The player is free to select a new race, appearance and class for the character. Ultimately, this allows the player to make an entirely new, stronger character.[citation needed]

Epic reincarnation is only available to characters at the level cap. Characters lose their epic experience and start again at level 20, receiving an epic past life feat.

Dungeons & Dragons Online: Stormreach was developed by Turbine over two years. The initial prototype and concept were done by Jason Booth, Dan Ogles, Cardell Kerr, Ken Troop, and Michael Sheidow, in coordination with Wizards of the Coast, the publisher of Dungeons & Dragons.

On August 1, 2005, Turbine sent invitations to people interested in participating in the public alpha test. On November 1, 2005, Turbine announced that the public beta test was open.[18] On November 22, 2005, Turbine announced that each copy of the January 2006 issue of PC Gamer magazine would contain a key to gain access to the beta. Turbine, in association with Fileplanet and IGN, completed three public stress tests of the game, with the last ending on February 12, 2006.

After testing was complete, a special head start event began on February 24 for those who pre-ordered, with the game opening to the public on February 28.[19] As of April 2008, there were less than 100,000 subscribers for the game.[20] In June 2009, DDO reopened beta testing, in preparation for their new free-to-play subscription structure.[21]

Turbine originally released major content updates as modules, in keeping with the module concept in D&D. Additional content was released between modules as updates. Responding to player feedback that the interim updates did not provide enough new content, the development team stopped releasing them, beginning with Module 5, instead focusing on creating larger modules. Prior to the launch of DDO: Eberron Unlimited, there was a 10-month content gap.[citation needed]

On June 9, 2009, the official D&D Online website announced that Dungeons & Dragons Online would convert to a subscriptionless "free to play" game for players in North America, under the new name Dungeons & Dragons Online: Eberron Unlimited. The level cap would be increased to level 20 and free users would have access to the majority of game content; some features would have to be purchased with Turbine points or unlocked through play. There would be VIP access with additional features available, as well as free Turbine points. Closed beta registration opened on June 9, 2009. The game and contents were free to download on September 1 for VIP members and September 9 for the general North American public.[22]

Turbine presented its new "Menace of the Underdark" expansion module at the PAX East convention in April 2012,[23] before releasing it in June.[24] The expansion increased the maximum character level and added the druid class.[25]

On August 24, 2009, Turbine, Inc. filed lawsuit against Atari claiming a breach of a licensing agreement for Dungeons & Dragons. The suit alleged six counts over six years, including consistent breaches of contract, a lack of promotion and distribution, and attempting to gain additional money from Turbine's licensing of the D&D properties. Furthermore, Turbine claimed that many of the maneuvers by Atari were designed to either undercut the upcoming launch of Dungeons & Dragons: Eberron Unlimited or help Atari launch its own competing MMO.[41] Atari filed a motion to dismiss the lawsuit, and also filed a separate complaint to recover monies owed to Atari resulting from an independent third party audit of Turbine.[42] The case was settled out of court in 2011.[43]

Ontario-based web services company Treehouse Avatar Technologies Inc. filed a patent infringement lawsuit against Turbine, Inc., which claimed Dungeons & Dragons Online game had violated United States Patent No. 8,180,858 (Method And System For Presenting Data Over A Network Based On Network User Choices And Collecting Real-Time Data Related To Said Choices), which was awarded on May 15, 2012.[44][45]Wi-Lan Inc., a publicly traded Canadian company, is the owner of the patent.[46][47]